Develop Reference

How to set List Adapter in onPostExecute Asynctask?

Good Day everyone,
I have some problem here. I make a web service call in AsyncTask DoInBackground.
And I wanted to set list adapter, but I got error
java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
Now how to set list adapter in post execute or something?
My code
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_profile);
progressBar = (ProgressBar)findViewById(R.id.prgLoading);
//Initialize the ListView
final ListView lvProf = (ListView)findViewById(R.id.lvProfile);
//call the asynctask cals and add item to the list.
new LoadDataForActivity().execute();
//Set adapter , but i got error here
lvProf.setAdapter(new ListProfileAdapter(this,mItems));
}
private class LoadDataForActivity extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
getWindow().setFlags(WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,
WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE);
progressBar.setVisibility(View.VISIBLE);
progressBar.setIndeterminate(false);
progressBar.setClickable(false);
}
#Override
protected Void doInBackground(Void... params) {
getAll();
getTotalLeaveBalance();
getMedicalBalance();
return null;
}
#Override
protected void onPostExecute(Void result) {
//here is I add the item to my list (mitems)
try{
ResponseServiceMedicalBalance = ResponseServiceMedicalBalance.replace("\\\"", "\"");
ResponseServiceMedicalBalance = ResponseServiceMedicalBalance.substring(1, ResponseServiceMedicalBalance.length() - 1);
JSONParser jsonParser = new JSONParser();
JSONObject jsonObject = (JSONObject) jsonParser.parse(ResponseServiceMedicalBalance);
String Status = jsonObject.get("Status").toString();
if (Status == "true") {
// JSONArray structure = (JSONArray) jsonObject.get("DataList");
String dataku = jsonObject.get("DataList").toString();
mItems = new ArrayList<ListProfileItem>();
try {
dataku = ANGGACRYYPT.decrypt(Enc_Pass, dataku);
}catch (GeneralSecurityException e){
//handle error - could be due to incorrect password or tampered encryptedMsg
}
JSONParser parser = new JSONParser();
JSONArray structure = (JSONArray) parser.parse(dataku);
for (int i = 0; i < structure.size(); i++) {
JSONObject data = (JSONObject) structure.get(i);
item = new ListProfileItem();
item.claimpostname = data.get("claim_post_name").toString();
String claimamount = data.get("max_limit_per_year").toString();
if (claimamount!=("0.0"))
{
Double amount = Double.parseDouble(claimamount);
DecimalFormat formatter = new DecimalFormat("#,###.00");
String AmountFormatted = formatter.format(amount);
item.claimpostamount = AmountFormatted;
}
else
{
item.claimpostamount = data.get("max_limit_per_year").toString();
}
mItems.add(item);
}
// initialize and set the list adapter
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
}

There are several ways of solving this, One of the quick and dirtiest is:
Change your AsyncTaskActivity Like this:
private class LoadDataForActivity extends AsyncTask<Void, Void, Void> {
private ListView listView;
private Context context;
public LoadDataForActivity(ListView listView,Context context){
this. listView = listView;
this.context = context;
}
#Override
protected void onPreExecute() {
getWindow().setFlags(WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,
WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE);
progressBar.setVisibility(View.VISIBLE);
progressBar.setIndeterminate(false);
progressBar.setClickable(false);
}
#Override
protected Void doInBackground(Void... params) {
getAll();
getTotalLeaveBalance();
getMedicalBalance();
return null;
}
#Override
protected void onPostExecute(Void result) {
//here is I add the item to my list (mitems)
try{
ResponseServiceMedicalBalance = ResponseServiceMedicalBalance.replace("\\\"", "\"");
ResponseServiceMedicalBalance = ResponseServiceMedicalBalance.substring(1, ResponseServiceMedicalBalance.length() - 1);
JSONParser jsonParser = new JSONParser();
JSONObject jsonObject = (JSONObject) jsonParser.parse(ResponseServiceMedicalBalance);
String Status = jsonObject.get("Status").toString();
if (Status == "true") {
// JSONArray structure = (JSONArray) jsonObject.get("DataList");
String dataku = jsonObject.get("DataList").toString();
mItems = new ArrayList<ListProfileItem>();
try {
dataku = ANGGACRYYPT.decrypt(Enc_Pass, dataku);
}catch (GeneralSecurityException e){
//handle error - could be due to incorrect password or tampered encryptedMsg
}
JSONParser parser = new JSONParser();
JSONArray structure = (JSONArray) parser.parse(dataku);
for (int i = 0; i < structure.size(); i++) {
JSONObject data = (JSONObject) structure.get(i);
item = new ListProfileItem();
item.claimpostname = data.get("claim_post_name").toString();
String claimamount = data.get("max_limit_per_year").toString();
if (claimamount!=("0.0"))
{
Double amount = Double.parseDouble(claimamount);
DecimalFormat formatter = new DecimalFormat("#,###.00");
String AmountFormatted = formatter.format(amount);
item.claimpostamount = AmountFormatted;
}
else
{
item.claimpostamount = data.get("max_limit_per_year").toString();
}
mItems.add(item);
}
listView.setAdapter(new ListProfileAdapter(context,mItems));
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
And you can call the asyncTask like this:
new LoadDataForActivity(listView,this).execute();

Initialise mItems as
mItems = new ArrayList<>();
Create object for ListProfileAdapter
ListProfileAdapter adapter = new ListProfileAdapter(this,mItems);
lvProf.setAdapter(adapter);
Add items in mItems
mItems.add(item);
After all items added to the list notify the adapter
adapter.notifyDataSetChanged();

move it from onCreate to onPostExecute()
define instance of Adapter as global variable then add Items in doInBackground() & call setAdapter onPostExec.
//Set adapter , but i got error here >> move it to onPostExecute
lvProf.setAdapter(new ListProfileAdapter(this,mItems));

I think the following line should be before setting your adapter,
mItems = new ArrayList<ListProfileItem>();
adapter = new ListProfileAdapter(this,mItems)
lvProf.setAdapter(adapter);
Make the instance variable,
ListProfileAdapter adapter;
instead of putting in the Asynctask. After finishing the asynctask in onPostExecute you also need to run,
adapter.notifyDatasetChanged();

ProgressDialog cannot stop when load JSON

please help, I've given up on finding a solution
Data json already be in ArrayList, nothing error found but the progressdialog can't stop loading. I'm already put PG.dismis in postExecute but even the Adapter cannot changed.
private static List<DataVoucher> processResponse(String response) {
List<DataVoucher> list = new ArrayList<DataVoucher>();
try {
JSONObject jsonObj = new JSONObject(response);
JSONArray jsonArray = jsonObj.getJSONArray("produk");
Log.d(TAG, "data lengt: " + jsonArray.length());
DataVoucher dataVoucher = null;
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject obj = jsonArray.getJSONObject(i);
dataVoucher = new DataVoucher();
dataVoucher.setKode(obj.getString("kode"));
dataVoucher.setHrg(obj.getString("hrg"));
dataVoucher.setNom(obj.getString("nom"));
dataVoucher.setKet(obj.getString("ket"));
list.add(dataVoucher);
listvoucher.add(obj.getString("nom"));
}
} catch (JSONException e) {
Log.d(TAG, e.getMessage());
}
return list;
}
public static String requestDataVoucher(final String operator) {
final String TAG = "SEND JSON";
Thread thread = new Thread() {
public void run() {
Looper.prepare();
JSONObject jsonObjSend = new JSONObject();
try {
jsonObjSend.put("type", "svoc");
jsonObjSend.put("hp", "089631633614");
jsonObjSend.put("opr", operator);
Log.i(TAG, jsonObjSend.toString(2));
} catch (JSONException e) {
e.printStackTrace();
}
SendHttpPost(jsonObjSend);
Looper.loop();
}
};
thread.start();
return TAG;
}
private class MainActivityAsync extends AsyncTask<String, Void, String> {
#Override
protected void onPreExecute() {
progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setMessage("retrieving...");
progressDialog.setIndeterminate(false);
progressDialog.setCancelable(false);
progressDialog.show();
}
#Override
protected String doInBackground(String... params) {
String response = requestDataVoucher(pilihOperator
.getSelectedItem().toString());
list = processResponse(response);
return null;
}
#Override
protected void onPostExecute(String result) {
adapter = new ArrayAdapter<String>(MainActivity.this,
android.R.layout.simple_spinner_item, listvoucher);
adapter.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line);
pilihVoucher.setAdapter(adapter);
adapter.notifyDataSetChanged();
if (!adapter.isEmpty()) {
progressDialog.dismiss();
} // this is annoying
}
}

adapter = new ArrayAdapter(MainActivity.this,
android.R.layout.simple_spinner_item, listvoucher);
I think u mean
adapter = new ArrayAdapter(MainActivity.this,
android.R.layout.simple_spinner_item, list);
Btw just dismiss ur progressDialog at onPostExecute() not checking anything and maybe warn the user if the list is empty so you will evade these problems.

Many issues here
doInBackground is running in a thread, different from the ui thread. You are calling requestDataVoucher which is also creating a new thread, useless in this case.
You are calling processResponse with the String response which is the result of requestDataVoucher. According to your code, response equals "SEND JSON". So JSONObject jsonObj = new JSONObject(response); will trigger an Exception, listvoucher will remain empty, and so will your adapter. Conclusion, adapter is empty, the progressDialog won't disappear.
I can't propose a fix, as SendHttpPost is unknown. But as far as goes my understanding, you should remove the Thread creation from requestDataVoucher and return the JSON String generate by SendHttpPost.

Empty listView in listFragment

I have a list fragment. When I run the app, I see an empty listView.
I don't know what the problem is. Maybe I should use a library?
public class MyEmployeFragment extends ListFragment {
private static final String ATTRIBUTE_ID = "p_id";
private static final String ATTRIBUTE_NAME = "p_name";
private static final String ATTRIBUTE_LAST_NAME = "p_last_name";
ArrayList<spr_item> ret_data;
MyTask task;
SimpleAdapter sAdapter;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
task = new MyTask();
task.execute();
return inflater.inflate(R.layout.my_employe, null);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
ret_data = new ArrayList<spr_item>();
ArrayList<Map<String, Object>> data = new ArrayList<Map<String, Object>>(
ret_data.size());
Map<String, Object> m;
for (int i = 0; i < ret_data.size(); i++) {
m = new HashMap<String, Object>();
m.put(ATTRIBUTE_ID, ret_data.get(i).getId());
m.put(ATTRIBUTE_NAME, ret_data.get(i).getName());
m.put(ATTRIBUTE_LAST_NAME, ret_data.get(i).getLastName());
data.add(m);
}
// массив имен атрибутов, из которых будут читаться данные
String[] from = {ATTRIBUTE_ID, ATTRIBUTE_NAME, ATTRIBUTE_LAST_NAME};
// массив ID View-компонентов, в которые будут вставлять данные
int[] to = {R.id.tw_employe_id, R.id.tw_employe_name, R.id.tw_employe_last_name};
// создаем адаптер
sAdapter = new SimpleAdapter(getActivity(), data, R.layout.list_item_employee,
from, to);
// определяем список и присваиваем ему адаптер
ListView lvSimple = (ListView) getView().findViewById(android.R.id.list);
lvSimple.setAdapter(sAdapter);
}
class MyTask extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Void doInBackground(Void... params) {
String s = "5ACACEC6-752B-4EFF-AA50-EEBE58A52113";
// String user_guid = myPrefs.getString("guid", "");
HttpActivity _http = new HttpActivity("192.168.10.11", "80");
_http.set_addr_protocol("/WebSite/P/spr/spr.aspx/");
_http.add_param("query", "spr_employee_get");
// _http.add_param("p_guid", user_guid.toString().trim());
_http.add_param("p_guid", s);
_http.send();
List<spr_item> tempList = _http.getArrayParamValue();
for(int i = 0; i < tempList.size(); i++)
ret_data.add(tempList.get(i));
//employer_name = _http.getArrayParamValue("p_name");
//employer_id = _http.getArrayParamValue("p_id");
//employer_last_name = _http.getArrayParamValue("p_last_name");
return null;
}
protected void onPostExecute(Void result) {
super.onPostExecute(result);
sAdapter.notifyDataSetChanged();
}
}
}

With the above code apart from the Empty list you may have the null pointer exception too if the task is too quick to load. Here onCreate is called first onCreateView next and onActvityCreated next. So it is better to initialise adapter in onCreate set the adapter to listView in onCreateView and set listView listeners in onActvityCreated using getListView() method.
Apart from this if you are using local database to retrieve data you need to use cursorADapter to fetch the data

The adapter's data references (ArrayList, array, etc.), tend to get lost pretty easily. In that case the notfiyDataSetChanged() method will not work. If you are adamant on using this method I suggest you check the references to the adapter's source again. If that is not the case this is the approach I've used in my project. A small warning in advance, the formatting and the closing of brackets is poorly executed, but the approach is still clear enough.
public class MyFragment extends ListFragment {
// For populating the list view.
SomeAdapter adapter;
public MyFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
String[] parameters = {"url for request"};
new GetRequestTask().execute(parameters);
}
// The async task to make the HTTP GET requests.
class GetRequestTask extends AsyncTask<String, String, String>{
#Override
protected String doInBackground(String... uri) {
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response;
String responseString = null;
try {
response = httpclient.execute(new HttpGet(uri[0]));
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpStatus.SC_OK){
ByteArrayOutputStream out = new ByteArrayOutputStream();
response.getEntity().writeTo(out);
out.close();
responseString = out.toString();
} else{
//Closes the connection.
response.getEntity().getContent().close();
throw new IOException(statusLine.getReasonPhrase());
}
} catch (ClientProtocolException e) {
Log.e("GetRequestTask", "Client protocol exception.");
e.printStackTrace();
} catch (IOException e) {
Log.e("GetRequestTask", "IO exception.");
e.printStackTrace();
}
return responseString;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
// Update UI with the new response.
new UpdateUITask().execute(result);
}
}
}
// The async task to update the UI.
class UpdateUITask extends AsyncTask<String, String, ArrayList<Something>>{
#Override
protected ArrayList<Something> doInBackground(String... input) {
ArrayList<Something> someArray = new ArrayList<Something>();
try{
// Do some JSON magic to parse the data.
}
catch(JSONException je){
Log.e("UpdateUITask", "JSON parsing error occured.");
je.printStackTrace();
}
return someArray;
}
#Override
protected void onPostExecute(ArrayList<Something> result) {
super.onPostExecute(result);
Log.i("UpdateUITask", "Updating UI.");
adapter = new SomeAdapter(getActivity(), R.layout.some_list_item, restOfTheParameters);
setListAdapter(adapter);
}
}
}
}

[AsynTask][Restful Client(Android user)][Spring framework] ArrayList of Class from doInBackground to onPostExecute

Following is resful web service display on browser.I need to read these data info andoird as client side as list of table
ArrayList<PickerItemDetail>
//content of http://127.0.0.1:8080/picking
[
{"pickerBatch":1,"sku":"FL45678976543","name":"Coke 1000L","image":"coke.jpg","qty":"8","pickingStatus":"picked","pickedBy":"John","pickedOn":"02/04/2014","locked":"0"},
{"pickerBatch":2,"sku":"FL45678543675","name":"Mineral Water 50L","image":"drinkingWater.jpg","qty":"5","pickingStatus":"picked","pickedBy":"Roy","pickedOn":"02/04/2014","locked":"0"}
]
For android side
public class MainActivity extends ListActivity {
#Override
protected void onStart() {
super.onStart();
new HttpRequestTask().execute();
}
private class HttpRequestTask extends AsyncTask<Void, Void, ArrayList<PickerItemDetail>> {
#Override
protected ArrayList<PickerItemDetail> doInBackground(Void... params) {
try {
final String url = "http://127.0.0.1:8080/picking";
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
ArrayList<PickerItemDetail> item = restTemplate.getForObject(url, ArrayList.class);
return item;
} catch (Exception e) {
Log.e("MainActivity", e.getMessage(), e);
}
return null;
}
#Override
protected void onPostExecute(ArrayList<PickerItemDetail> item) {
TextView sku = (TextView) findViewById(R.id.sku);
TextView qty = (TextView) findViewById(R.id.qty);
TextView name = (TextView) findViewById(R.id.skuname);
sku.setText(item.get(0).getSku());
qty.setText(item.get(0).getQty());
name.setText(item.get(0).getName());
}
}
}
I would like to read list of data from webservice then display it as a table in android side.
How do I have a proper code to loop over the ArrayList,I think these code not fully correct way,but no idea to continue/make it pretty works.
onPostExecute(ArrayList<>){ item.get(0).getXXX}
Hope someone advice
,Thank

I am not sure what exactly you need but if you want show in listview you can go with
like this.... in your postexecut=sion
add this function loadData();
loadDate() function will be like
private void loadData() {
try {
// looping through All Contacts
contactList.clear();
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
// Storing each json item in variable
String pickerBatch = c.getString("pickerBatch");
String sku = c.getString(sku);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put("pickerBatch", pickerBatch);
map.put("sku", sku);
// adding HashList to ArrayList
contactList.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
ListAdapter adapter = new MySimpleAdapter(Activity.this,
contactList, R.layout.list_item, new String[] {
pickerBatch, sku }, new int[] {
R.id.pickerBatch, R.id.sku });
setListAdapter(adapter);
//
// /
// selecting single ListView item
}
In this above example contactList is your arrayList... Hope it will work

Android - Populate list with AsycTaskLoader & MySql

I want to fill a ListFragment with certain objects loaded from my MySql database.
It has to load the first 10 'objects' from my ResultSet.
I want to use an AsyncTaskLoader for this and put the loaded object in a ListItem each time I retreive it from the database.
Can anybody help me with this one? Tried searching for good examples or tutorials but I haven't really found something that's really useful...

Create your adapter with a new list in your preexecute method. Set that adapter to your listview.
Then in doInBackground read your database, create objects to fit in your list, but don't add them. Pas each object after made as parameter for your publishprogress method.
In onProgressUpdate add your object to the list and notify your adapter that the dataset is changed.
Below is an example for how I do it reading a twitter call.
private class parseTwitterTask extends AsyncTask<Void, TCListObject2, List<TCListObject2>> {
TCListObjectAdapter2 adapter;
List<TCListObject2> list;
#Override
protected void onPreExecute() {
list = new ArrayList<TCListObject2>();
ListView lv = (ListView)findViewById(R.id.twitterlist);
adapter = new TCListObjectAdapter2(list);
lv.setAdapter(adapter);
super.onPreExecute();
}
#Override
protected List<TCListObject2> doInBackground(Void... params) {
try {
String url = social.get("twittersearchurl");//"http://search.twitter.com/search.json?q=" + social.get("twitter");
String json = Internet.request(url, null);
JSONObject jo = new JSONObject(json);
if(jo.has("results")) {
JSONArray ar = jo.getJSONArray("results");
for(int i = 0; i < ar.length(); i++) {
TCListObject2 tweet = new TCListObject2();
JSONObject jobj = (JSONObject) ar.get(i);
tweet.id = "false";
tweet.img = jobj.getString("profile_image_url");
String text = jobj.getString("text");
text = Html.fromHtml(text).toString();
tweet.params.put(R.id.sub2, text);
String name = jobj.getString("from_user");
name = Html.fromHtml(name).toString();
tweet.params.put(R.id.text, name);
String time = jobj.getString("created_at");
tweet.params.put(R.id.sub1, Converter.timeToTimeAgo(time));
try {
tweet.time = new Date(time);
} catch(Exception e) {
e.printStackTrace();
}
tweet.celLayout = R.layout.cell_tweetobject;
publishProgress(tweet);
}
}
} catch(Exception e) {
e.printStackTrace();
}
return list;
}
#Override
protected void onProgressUpdate(TCListObject2... values) {
list.add(values[0]);
adapter.notifyDataSetChanged();
super.onProgressUpdate(values);
}